In recent years, rotary electric machines such as an electric motor and an electric generator are required to have a small size, high output, and high quality. Therefore, an armature using an armature winding having a distributed winding structure, which can suppress torque pulsation and enables increase in output, is required. Further, because of rising of the magnet price, demand for rotary electric machines not using magnets also increases, and an armature using an armature winding of a distributed winding type and having a higher efficiency is required. It is noted that a winding of a concentrated winding type is configured by winding a conductive wire around one tooth, whereas an armature winding of a distributed winding type is configured by winding a conductive wire in slots separated from each other by two or more slots. That is, winding is made such that a conductive wire leading out from one slot is inserted into another slot across two or more consecutive teeth.
In a conventional method for manufacturing an armature having an armature winding of a distributed winding type, the armature is mass-produced using a device called an inserter for inserting a coil. The armature manufactured by this method has a structure called concentric winding in which coil ends are arranged concentrically. In this structure, interference between the coil ends increases, leading to increase in the size of the armature. On the other hand, in lap winding which is one type of distributed winding and in which the coil ends are arranged in a volute shape, the coil ends less interfere with each other. Therefore, the coil ends can be made smaller than those in the case of concentric winding, and size reduction can be achieved. However, because of the configuration, it is impossible to perform assembling from one direction, and therefore it is difficult to achieve automation. Accordingly, a coil retaining device as an annular conductor retaining device is proposed in which, when annular conductors to be coils are retained in a lap winding shape in the coil retaining device, a plurality of annular conductors are retained by each of two main retaining portions which are movable and have semi-cylindrical shapes (which can be a cylindrical shape when integrated), the main retaining portions are moved to be integrated into a cylindrical shape so that the annular conductors retained by the respective main retaining portions overlap each other, and then the annular conductors are inserted into slots of a core (see, for example, Patent Document 1).
In a coil arrangement method in another conventional method for manufacturing an armature, in an arrangement step S, a plurality of annular conductors are arranged so as to overlap each other in an inclined state in a coil retainer having a plurality of blades arranged in a cylindrical shape. This arrangement step includes a normal arrangement step and a special arrangement step. In the normal arrangement step, normal annular conductors are sequentially inserted in accordance with an arrangement order defined by a normal arrangement direction as long as insertion operation is possible. The normal arrangement step is finished when the next insertion operation is impossible. Then, the rest of the annular conductors (annular conductors that cannot be inserted in the same manner as the other normal annular conductors) are provided as specific annular conductors in the subsequent special arrangement step. In the special arrangement step, each of the plurality of specific annular conductors is inserted being inclined in the opposite direction with respect to the normal annular conductors arranged in the normal arrangement step (see, for example, Patent Document 2).